AlbertaRam

Hi all, I have a 2012 3500 megacab with full delete (DEF, EGR, TV) and and EFI live 163000 KM's (101000 miles?). It supposedly has ARP studs in it but I don't know for sure. Recently it started overheating on the 3rd of the 5 tunes, so I turned it down and only run on the lowest tune since. A week ago it over heated again. and now manages to puke all the coolant out into the overflow when warm. I changed the thermostat, changed the rad cap, am pretty sure its not the sensor as that would make it seem to be hot without actually puking the coolant (wouldn't it?). So I took it to the shop and they had a look at it, ran the syringe on the rad and said there was no exhaust in the coolant, they let it run up to temp and retested again no fumes. I had them change the oil and checked, dark black and healthy oil. So I had no choice but to pay and leave with it as is. It was good for a few days or so then back to the same thing again, this time I noticed it blows cold air out of the vents just before over heating, as well as gurgling after shut down. I did notice a slight leak on the rear EGR block off plate, and there is a steel line (small maybe 1/4" wide) that runs from the back of the head to the sender area, that was ice cold even when the engine was over heating. Not sure what it is. I also noticed the exhaust note is louder under the passenger front engine compartment, I have yet to track down the leak due to being away at work. The turbo whistle sounds normal when cold, but goes away when warm. I have not tested for boost leaks. There is no white smoke upon start up, no coal when floored (lowest tune though).

About 8000 km ago (5000mile) I had the front seal (crank) changed, the fan clutch belt tensioner, the fan hub bearing and the t case output seal all replaced. I don't know what, but is there any chance any of that could be the problem? Or any other ideas or thoughts?

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Sounds like compression gasses pressurizing the radiator. Any possibility of just air being trapped in the system? Who did the deletes and the head studs?

AlbertaRam

Actually, I went back and checked the coolant level, it was down of course and you got me wondering if the last time they worked on the truck was the cooling system bled? So I took a trick from my dad's bag of tricks (old farmer) and cut the big end off a 2L Coke bottle, stuck it in the top of the rad, wrapped it with electrical tape, and then added coolant until the bottle was 1/2 full. Shut the heater off, then started the truck and let it run until the temp came up. And sure as hell, the coolant in the bottle, burped, bubbled and dropped, then turned the heater on full for 5 minutes, just to be sure. Shut the truck off, pulled the bottle off (let the extra run into a tray (I hate a wet shop floor), put the rad cap back on and drove her for 1/2 hr including some hard work. Temp went exact;y where it should and no higher. Shut her down, still a bit of gurgling, but waaaaay less. So tomorrow I'll repeat and hopefully get the last of the air.

Whew!

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I beleive there is an air bleed on the side of the head. Shold be a silver set screw looking thing. You can also take the top radiator hose off and hold one end higher than everything and fil it from that. But it sounds like air may have been the issue.